Various subtypes of nicotinic acetylcholine receptors (nAChRs) are present in muscle tissue, in the brain and cells of the nervous and immune systems, in epithelial and other cells, performing a number of vital functions in them, while dysfunction of nAChRs leads to disruptions in the functioning of these systems, being one of causes of myasthenia gravis, mental and neurodegenerative diseases, inflammatory processes, as well as carcinogenesis. In nAChR studies, an important role is played by peptides and proteins from venoms of various animal species and their modified derivatives, which act as specific antagonists of distinct nAChR subtypes. Our team has a large collection of protein neurotoxins from snake venoms and their fluorescent and radioactive derivatives, used to characterize various subtypes of nAChRs, namely muscle-type receptors, neuronal-type receptors present in the brain (neuronal nAChRs), as well as so-called non-neuronal ones (identical in subunit composition with neuronal ones), located not in the brain, but on the cells of the immune system and in various other tissues. The finest tools for distinguishing nAChR subtypes are α-conotoxins, peptide neurotoxins from poisonous marine mollusks. This collection of protein and peptide cholinergic ligands, supplemented also by low molecular weight compounds, is used by us in studies of various nAChRs, recently concentrated on the α7 and α9α10 subtypes. The data available in the literature and ours indicate that a number of such toxins inhibit the proliferation of tumor cell lines. For some α7 nAChR agonists, the ability to inhibit inflammatory processes and immunosuppression has been discovered. For the natural alkaloid 6-bromohypaphorine we discovered agonistic activity against α7 nAChR and created a series of synthetic analogues with significantly increased affinity and anti-inflammatory and analgesic activities. The particular scientific novelty of the project lies in the detailed study of the functional role of not only α7, but also other nAChR subtypes , including the α9α10 receptor. Our preliminary data suggest the possibility of mutual influence of the activity of these two receptor subtypes in immune cells. The main objective of this project is to obtain, using the existing set of selective cholinergic antagonists and agonists, new data on the presence and functional activity of various nAChR subtypes (with priority attention to α7 and α9α10) in a line of cancer cells, including immune ones. Since a number of oncological diseases require nAChR inhibition, we will test the effect of oligoarginines, a new class of non-toxic inhibitors of some types of this receptor that we have discovered. The relevance of the planned study is evidenced by the available data on the participation of nAChRs in a wide range of physiological and pathophysiological processes in the body. An important objective of the project is to evaluate the effect of cholinergic agonists and antagonists on the mRNA levels of the entire set of nAChR subunits, as well as some other receptors, such as A-type γ-aminobutyric acid receptors (GABA A receptors), which, like nAChRs , belong to the Cys-loop receptors, some of which are affected (as shown in our and foreign laboratories) by α-neurotoxins. Analysis of the functional activity of neuronal nAChRs (including α7 and α9α10 subtypes, as well as GABAA receptors) will be carried out on a wide range of cancer cells, including lymphomas, glioblastomas, lung, liver, pancreas, breast, kidney, prostate, ovary, and others. It will reveal the anti-inflammatory and anti-immunosuppressive effects of some compounds from the existing series of agonists. By studying the action of cholinergic antagonists, it will be possible to identify promising antiproliferative substances. The effects of agonists and antagonists will be recorded using radioligand and enzyme immunoassays, real-time PCR, fluorimetry, cytometry and electrophysiology, which we have previously used. We expect to obtain qualitatively new results through the planned use of quantitative proteomics to analyze changes caused in cells by the addition of agonists or antagonists. The project is based on our recent work to elucidate the role of one of the selective α7 nAChR agonists in the cholinergic anti-inflammatory pathway in macrophages, on discovery of anti-inflammatory and analgesic activities for 6-bromohypaphorine analogues, and on analyzing the effect of α-neurotoxins and α-conotoxins on the growth of a number of tumor cells , as well as on proteomic and transcriptomic studies of viper venom. The scientific novelty of the expected results consists in obtaining new information about the participation of certain nAChR subtypes in a number of physiological and pathophysiological processes, which will open up new opportunities for the creation of drugs.